AT SEA - APRIL 14:  In this handout image provided by Commonwealth of Australia, Department of Defence, Phoenix Autonomous Underwater Vehicle (AUV) Bluefin-21 is in the water after being craned over the side of Australian Defence Vessel Ocean Shield to begin using its side scan sonar in the search for the missing Malaysia Airlines flight MH370 on April 14, 2014. Twenty-six nations have been involved in the search for Malaysia Airlines Flight MH370 since it disappeared more than a month ago. (Photo by LEUT Kelli Lunt/Australia Department of Defence via Getty Images)

The Bluefin-21 uses its side scan sonar in the search for the missing Malaysia Airlines flight MH370. Photo: Getty Images

With two-thirds of the search area scoured by an underwater autonomous vehicle, the search for Malaysia Airlines flight MH370 is yet to find any sign of the plane.

Bluefin-21 is below the water on its ninth mission.

The focused underwater search area is a circle of 10 kilometres radius around the second towed pinger locator detection, which occurred on April 8.

It is understood that those coordinating the search are considering bringing in further equipment for the underwater search.

A total of 10 ships will assist in Tuesday's search.

Crews will have to deal with scattered showers and sea swells of up to three metres.

Another 10 aircraft were scheduled to assist in the search but the air search was suspended on Tuesday morning due to poor weather conditions.

The four aircraft that had already departed before the aerial search was called off will continue with their missions, however, individual aircraft captains will assess the conditions once they reach the search area and decide whether or not to continue or return.

The Australian Maritime Safety Authority has planned a visual search area totalling approximately 49,491 square kilometres for the day.

The centre of the search area lies approximately 1584 kilometres north west of Perth.

The Bluefin-21 takes about two hours to descend and is capable of scanning parts of the search area for 16 hours before taking another two hours to return to the surface.

This would allow a five kilometres by eight kilometres area to be searched.

Analysing data from the device can take up to four hours.